The overall aims of this project are to elucidate the mechanisms of regulation of heart glycogen synthase and its interconverting kinases and phosphatases in response to hormonal stimulation and/or nutritional stress. This project will involve: 1) the characterization of the phosphorylation of beef heart glycogen synthase I by cAMP-dependent and -independent protein kinases, 2) the isolation of the protein phosphatases which act on the different phosphorylated forms of the glycogen synthase, 3) determining the manner in which the cAMP-independent protein kinase and protein phosphatase activities are regulated and 4) the correlation of the in vitro generated multiple phosphorylated and kinetically different forms for glycogen synthase with the generation of the multiple kinetic forms generated in vivo in response to hormones and/or nutritional stress.